Scotland manager George Burley has explained the three surprise call-ups to his squad for the friendly against Northern Ireland at Hampden on August 20.

Derby County winger Kris Commons, an Englishman who qualifies through his
grandparents, is joined by Falkirk skipper Darren Barr, who is also named in the
senior squad for the first time.

Preston defender Callum Davidson returns to the Scotland set-up at the age of
32 after six years in the wilderness.

On Commons, Burley said: 'I became aware that Kris could qualify for Scotland
a few months ago. I saw a lot of him when I was manager of Derby and he was at Nottingham
Forest.

'He transferred to Derby in the summer and I had him watched. I think he will give us a different dimension. He is a boy with a lot of
ability, he is a naturally left-sided winger and maybe we have lacked width in
the squad.

'I spoke to the boy and he was keen and enthusiastic to join the squad.'

Burley insists Barr and Davidson, who has been capped 17 times, bring a mixture
of youth and experience to his squad for what will be the last friendly match
before the 2010 World Cup qualifiers begin next month with a double-header
against Macedonia and Iceland.

The Scotland boss said: 'Callum is an experienced player who has played for
Scotland in the past. He did very well for Preston and I watched him in a pre-season game against
Motherwell.

'He is fit and injury-free and this is an opportunity to look at him. Darren Barr is one for the future. He was involved with the B squad last year
and he is still finding his way.

'But this was another good opportunity to bring a young player in.'

Scotland squad to play Northern Ireland in a friendly at Hampden on August 20: